The recovery of oil and other valuable liquids from the ground typically involves the drilling of a borehole from the surface to the depth necessary to contact the oil or fluid reservoir. The drilling device is then removed and a casing having a circular cross section is positioned in the borehole. The casing prevents collapse of the borehole as well as serving other purposes.
A common technique for pumping the oil to the surface from the borehole includes a pumping unit mounted on the surface. Sucker rods extend from the pumping unit to a pump located beneath the oil level in the borehole. The pumping unit reciprocates the sucker rods in the vertical direction which operates the pump to lift the oil to the surface. This technique requires complex equipment which occupies considerable space on the surface. The sucker rods are mechanically interconnected between the pumping unit at the surface and the pump within the borehole which requires the pumping unit to be accurately positioned above the well bore.
Several attempts have been made to simplify and improve the pumping operation. One example of such an attempt is described and illustrated in U.S. Pat. No. 2,702,005 to Kruse, issued Feb. 15, 1955. However, there remains a need for a pump for oil or other fluids having increased reliability and cost effectiveness.